Horizontal continuous casting is commonly used in the production of metal ingots from molten metal. Continuous casters can produce ingots of various cross-sectional shape and girth, by varying the casting mould used in the caster. Ingots can then be cut to desired lengths downstream of the caster. An example of a conventional horizontal continuous caster can be seen in, for example, U.S. Pat. No. 3,455,369.
Multi-strand horizontal casters are a particular type of caster, which allow multiple strands of ingots to be cast at the same time. Such casters generally have a molten metal feed trough connected to multiple casting moulds either via a single header box or via dedicated separate connecting troughs for each mould.
It is often required to temporarily isolate and shut down one or more strands in a multi-strand caster. Possible reasons for shutdown include upsets in either upstream or downstream operations, undesirable conditions of the molten metal, or general maintenance and repair of the caster. Improper isolation of the particular connecting trough during shut down can lead to loss of costly molten metal. There is also the possibility of fires or explosions if molten metal is not collected properly or comes into contact with water that is often used in cooling the ingots.
Attempts have been made to isolate and drain particular strands and collect molten metal during shutdown. An example of such a shut-off device can be seen in U.S. Pat. No. 4,928,779. However, such devices often require that the molten metal travel through the connecting trough and the casting mould and drain through the casting mould exit. This can cause molten metal to solidify in the casting mould and reduces access to this part, in case of repairs. As well, many shutdown systems only isolate the trough after molten metal has been sensed at the casting mould exit, so large quantities of molten metal are lost before the trough is isolated.
After the caster has been shut-down, and indeed at a time that the caster is to be started or restarted, it must operate in a manner that is both safe and minimizes any start-up losses of molten or cast metal. A common concern in startup is proper alignment of the cast ingot as it travels towards the cutting equipment. As well, metal leaving the casting mould is generally direct chilled by coolant sprays that impinge on the emerging ingot. In start up, it is important to prevent contact between the coolant and the molten metal, which can lead to explosions and fires.
Several start-up blocks have been devised for use with horizontal continuous casters. Some examples of these are shown in U.S. Pat. Nos. 4,454,907, 4,252,179, 3,850,225 and 4,381,030. However, most of these devices do not positively seal against the mould to prevent contact between molten metal and the coolant. Furthermore, many starter blocks permanently engage the emerging end of the ingot, so that the end of the ingot and the block must be cut from the ingot. This leads to undesirable waste of metal and the starter block.
It is therefore desirable to find shutdown methods and devices that will provide quick isolation of particular strands and rapid draining and collection of molten metal from all parts of the molten metal strand. It is also desirable to develop suitable starter bocks which can ensure proper alignment of the emerging ingot, and reduce chances of fire or explosion.
The invention makes it possible to use a remotely actuated shutoff device to terminate flow through one or more connecting troughs. After termination of flow, the invention also allows easy access to the connecting troughs and the mould.